# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/[^.]+\.(?=[^.]+$)//gm;t' <<< "// hash starts with number
/css/app.style.7fef363d5a8c4ef2458c.css
/css/app.bundle.7fef363d5a8c4ef2458c.css
/css/app.chunk.7fef363d5a8c4ef2458c.css
/css/app.7fef363d5a8c4ef2458c.css
/css/loading-animation.7fef363d5a8c4ef2458c.css
// hash starts with letter
/css/app.style.b3bcb606396f0c96623a.css
/css/app.bundle.b3bcb606396f0c96623a.css
/css/app.chunk.b3bcb606396f0c96623a.css
/css/app.b3bcb606396f0c96623a.css
// no preceeding dot separated name before the hash
/css/loading-animation.b3bcb606396f0c96623a.css
/css/app.b3bcb606396f0c96623a.js"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html